A rough graph of the amount of coffee sold as a function of price is as follows:
Work Step by Step
On the graph, represent the amount of coffee sold as the y value and the price of the coffee as the a: value. Now, expect that for a lower price, the store could expect to sell more coffee. Hence, the graph will start with a high y value, representing a large amount of coffee sold if the price, x, is low. The graph will start with some positive x value because we expect that the store would not want to give the coffee away for free. As the price, x, increases, the store would sell less coffee. So the amount of coffee sold, y, would decrease. Hence, the graph would go downhill as the graph moves to the right. As the price, x, continues to increase, the store would continue to sell less coffee until the coffee is so expensive that no one will buy any. Hence the graph will decrease until the amount sold, y, is 0.